This 'HW' caught my eye on July 17 2017 when I spotted it carved into a block on the very long time redundant 7 Arches Aqueduct in Adel Woods. The HW is quite worn but it looks as if it could have been more than a simple vandal carving of the initials. I wonder if anyone knows who HW was/is? Not knowing how old it is it could possibly be the initials of someone involved with the construction in the very early 1840s, though it may not be eroded enough for it to be that old.